Floating type mandrel for tube drawing



Oct. 3, 1944. c. H. WADELL FLOATING TYPE MANDREL FOR TUBE DRAWING Filed Dec. 24, 1945 INVENTOR I MJVWWL BY i ATTORNEY I m L kw Patented Oct. 3, 1944 Carl B. Wadell, Fairfleld, Coma, assignor to Bridgeport Brass Company, Bridgeport, Conn., a corporation of Connecticut Application December 24, 1943, Serial No. 515,588

14 Claims.

This invention relates to improvements in tube drawing apparatus, and more particularly to a floating mandrel plug and shank construction for use in connection with conventional draw-bench constructions and drawing dies. In my co-pending application Serial No. 479,425, filed March 17, 1943, of which this, application is a continuation in part, a construction has been described that is useful for tube drawing operations.

It is an object of the present invention to provide an improved form of such construction that is useful especially in the drawing of heavy gauge tubings or in reduction operations that require a long bearing die or any reduction operation that would allow metal to work in behind the tungsten carbide shell. In such operations it is necessary to provide means to prevent the tube from working in behind the sizing mandrel or sleeve because such an occurrence will result in breakage of the said mandrel or sleeve or in the bending of its supportingstud, and, consequently, result in waste and in loss of time. In addition sizing mandrels or sleeves are comparatively costly and breakagejs expensive. It isanother object of the invention to provide means that will eliminate the difilculties just discussed.

A further object or this invention is to pro-. vide a novel mandrel shank 'to be utilized with the sizing mandrel or sleeve whereby the latter will be less subject to breakage or damage when used particularly in the drawing of heavy gauge tubings or in reduction operations that require a long bearing die or any reduction operation, that would allow metalto work in behind the tungsten carbide shell.

To the accomplishment of the foregoing and I such other objects as may hereinafter appear, the invention consists in the novel construction and arrangement of parts hereinafter described and then sought to be defined in the appended Fig. 2 is a section taken along line 2-2 of Fig. 1 viewed in the direction of the arrows; Fig. 3 is a section taken along line 3-3 of Fig. 1, also viewed in the direction of the arrows:

Fig. 4 is .an end view of the mandrel construction viewed from the right of Fig. 1;

Fig. 5 is a longitudinal section taken along line 55 of Fig. 1 viewed in the direction of the placed within the die and tubing- 10. This construction 13 comprises a mandrel shank l4. This shank has a portion Iiiof enlarged diameter at one end. The enlarged portion I5 is provided with an enlarged countersunk or bore portion It to form a forwardly extending annular skirt portion II for a purpose to be presently described. A bored or countersunk portion I! of reduced diameter extends axially adjacent to the portion IS. A threaded bored portion I! of reduced diclaims; refer nce being had to the accompanying drawing fo merely for t e-purposes of illustrative disclosure, a preferred bodiment of the invention, it being expressly understood, however, that various changes may be made in practice within the scope of the claims without digressing from the inventive idea. J

In the drawing, in which similar reference characters denote corresponding partsz Fig. 1 is a longitudinal sectional elevation of a portion of a draw bench construction, its die and tubing being drawn, and shows the mandrel construction in position of use therewith;

ing a pal-thereof, which-shows,

ameter extends axially as a continuation of the portion It. An unthreaded portion 20 of further reduced diameter extends axially as a continuation of the portion l9 and the portion 20 connects with a bored portion 2i of still further reduced diameter in the body of the shank. The rear end of the shank I4 is provided with an axially extending threaded bored portion 22. The latter communicates with the bored portion 2| by a bored portion 23 of'reduce'd diameter. The bored portions is, l8, I9, 20, 2|, :2 and 2a are all in axial alignment and in eflect constitute a continuous bore through the shank having differing diameters invarious portions thereof as indicated.

A milled flat 24 for the use of a wrench may be provided in the shank ll 25 and 28 are oil holes drilled at desired angle to bore 2| to provide lubrication supplied through hollow plug rod 21. The shank ll is adapted to be screwed onto the plug rod 21. This plug rod 21 is supported in well known manner (not shown) during the drawing operation, for example in-the manner described in my aforesaid application.

' A retaining stud 28 is formed with a threaded .portion 29 which is adapted to threadedly ensage in the threaded portion l9 of'the shank.

This stud has a reduced end portion adapted to fit within the portion 26 of'the shank and an unthreaded portion 3| that extends outwardly of the shank. A head 32 is providedon the end of the outwardly extending portion 3|. This head has an annular abutment flange 33 and a rounded portion 34 of reduced diameter which may be provided with flattened sides 35 to permit application of a tightening tool or the like. The overall diameter of the flange 33 is less than the maximum outside diameter of the shank 4 The retaining stud 28 carries a loosely fitting sizing mandrel or sleeve 36. This sleeve 36 is substantially shorter than the portion 3| of the for a purpose to be presently described. The'internal diameter of the sleeve or mandrel 36 is substantially greater than the diameter of the portion 3| of the tud so that said sleeve or mandrel 36 may be movedor shiftedlaterally of as well as longitudinally with respect to the stud axis. The diameter of the bore l6 forming the skirt portion I1 is made large enough so that the skirt portion will not interfere with lateral displacement of said sleeve or mandrel 36. The outer wall 36a of the sleeve may be tapered if desired. The leading peripheral edge 36b of the sleeve 36 is tapered preferably with a 45 degree taper while its rearward or trailing peripheral edge 360 is rounded or tapered to any desired angle. 3

A suitable coil spring 31 is carried on the stud 26. This spring is adapted to be received in the bored portion l6 of the shank l4. 3 This spring is in compressed condition and abut the shoulder |6a of the bore l6 and the rearward or trailing end of the sleeve 36. The spring 31 serves to urge the sleeve 36 into abutment with the flange 33. The greatest shock to which the mandrel sleeve 36 is subject occurs when the tube l leaves said sleeve. The spring 31, however, also acts as a hazard of sleeve breakage at such time.

Preferably flange 33 has a smaller diameter than the diameter of the forward end of sleeve 36.

An alternative form of retaining stud may be used with the shank l4 in place of stud 28. Such a stud 40 is shown in Fig. 6. This stud 40 has a threadedportion 4| adapted to threadedly engage the threaded portion IQ of the shank. This stud 46 also has a reduced portion 42 adapted to fit within the bore of the shank and portions 43 and 44 forwardly of the threaded portion 4| of successively smaller diameters. The portion 43 is adapted to receive the spring 31 and the portion 44 is admeasured to receive the mandrel or sleeve 36. As with the stud 28, the portion- 44 has a substantially smaller diameter than the internal diameter of the sleeve or mandrel 36, :10 that the same lateral and longitudinal displacements of the sleeve or mandrel 36 may take place. A head 45 is provided on the outer end of the portion 44. This head has an abutment flange 46 and a head portion 41 similar in form and purpose to the corresponding parts 32 and 33 on the stud 26. It also has flattened sides 48 similar in purpose to sides 35. The overall outside diameter of the flange 41 is preferably less than the diameter of the leading end of the sleeve 36.

Either the stud 26 or thestud 46 may be used with the shank |4.' The stud 46 has some advantages in that it is lighter while being provided with necessary strength at those places'most subject to strain during use in tube drawing and allows standardization of thread diameters.

During the draw, imperfections on the inside surface of the tube, and lack of uniformity of tube thickness are compensated for by the lateral displaceability of the mandrel sleeve 36 with respect either to the stud 23 or 46. Thu in Fig.

5, the sleeve 36 is shown displacedfrom concentricity with respect to the axis of stud 26 to substantially the limit permitted by the differences in diameter between the portion 3| of the stud 23 and the internal diameter of the sleeve 36, a condition resulting from abnormally thick tubing wall on one side of the sleeve 36. Normally the sleeve 36 is self-centering, being positioned as shown in Fig. 1 when uniform wall thickness is encountered during the draw. The displaceability of the sleeve is of great importance as it eliminates breakage that would occur with a rigidly positioned mandrel, encountering tube conditions tending to produce the position of the sleeve 36 shown in Fig. '5.

Moreover, the skirt portion I overlaps the rear end of the sleeve 36 at all times so that itis impossible for the material of the tube III at any time to work in behind the rearward end of the sleeve 36 and'interfere with the functioning of the spring 31. This is very important especially when the sleeve is of cemented tungsten carbide Carboloy." "Carbo1oy is a, material rather weak in tensile strength and also weak in resisting shock. The spring 31 overcomes these drawbacks. During the time when the tube I II is being drawn the entire assembly comprising the rod 21 and appendages are under severe tensile stress. As soon as the tube l6 leaves the die ll these stresses are released very suddenly. When this release occurs, the sleeve would set up a compressive stressbetween the sleev and the shank |4 that would be likely to damage the sleeve. In the embodiment shown, when release occurs, the spring 31 absorbs the shock which in constructions embodying other form of constraining members have resulted in injury to the sleeve. Such shock absorption prevents injury to the sleeve 36 and renders practicable the use of Carboloy sleeves. If any tube metal could work itself in behind the sleeve, the action of the spring might be hampered. Thus the presence of skirt |1 eliminates such danger and renders the device practicable under all tube drawing conditions.

Another great advantage of the novel construction is that the same shank and stud can be utilized to mount replaceably several different sizes of mandrels or sleeves 36.

For example, with a stud diameter in portions 3| or 44 of .437 inch, mandrel sleeves each having an inside diameter large enough to permit floating action and respectively any outside diameter that allows sufllcient shell wall strength and clearance with respect to the skirt portion |1 may be used. Other sizes, too, are contemplated.

Another important advantage is that the mandrel construction described results in great economy. This is so because mandrel sleeves can be replaced on the same mandrel shank without any machining or fitting thereby making it unnecessary to provide separate mandrel shanks for each mandrel sleeve. The savings are in the order of twenty dollars per shank.

Economy also results from the fact that damage to the mandrel sleeve 36 adjacent either of its ends does not require that the sleeve be discarded. It may be trimmed oil to eliminate the damaged portions. In such event, the spring 31 may be replaced by a longer spring to compensate for the shortened sleeve length or the use of a shorter stud allows the same spring to be used. Since these sleeve mandrels are-very expensive, the savings are material and apparent.

In the embodiment described, the studs 28 and 40 are preferably oi heat-treated tool steel, the shank can be of any commercial tool steel that may be heat-treated while the sleeve mandrel is of cemented tungsten carbide, one commercially available material therefor being Carboloy.

While specific construction details have been described, and specific dimensional characteristics mentioned as well as specific materials, it is to be understood that variations in structure, dimensions and materials are contemplated within the scope of the claims. There is no intention of limitation to the exact details described.

7 What is claimed is:

l. A tube drawing mandrel construction comprising a mandrel shank, a stud threadedly engaging said shank, a sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve having a larger internal diameter than the external diameter of said stud, and said mandrel or sleeve being shorter than said stud whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, a retaining head on said stud, spring means on said stud for urging said mandrel or sleeve into abutment with said head, and a skirt portion extending from said shank, said skirt portion having a'larger internal diameter than the outer diameter of said mandrel or sleeve and being admeasured to overhang the rearward end of said mandrel or sleeve whereby to prevent the tube being drawn from working in behind said mandrel or sleeve.

2. A tube drawing mandrel construction comprising a mandrel shank having a threaded axially extending bore, a concentrically arranged skirt portion at one end of said shank, a stud threadedly engaging in said bore and extending outwardly of said skirt portion, a headed portion on said stud adjacent its outermost end, a sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve having a larger internal diameter than the external diameter of said stud,

being of shorter length than said stud and having a smaller external diameter than the internal diameter of said skirt portion whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud. and spring means on said stud for urging said mandrel or sleeve into abutment with saidhead, and said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in abutment with said head whereby to prevent tubing being drawn from working in behind said mandrel or sleeve.

3. A tube drawing mandrel construction comprising a mandrel shank having a threaded axially extending bore, a concentrically arranged skirt portion at one end of said shank, a stud threadedly engaging in said bore and extending outwardly of said skirt portion, a headed portion on said stud adjacent its outermost end, a sizing mandrel or sleeve removably carried on said stud,

said mandrel or sleeve having a larger internal diameter than the external diameter of said stud, being of shorter length than said stud and having a smaller external diameter than the internal diameter of said skirt portion whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, and spring means on said stud for urgin said mandrel or sleeve into abutment with said head, said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in abutment with said head whereby to prevent tubing being drawn from working in behind said mandrel or sleeve and said shank and stud being of tool steel and said mandrel or sleeve being of camented tungsten carbide.

4. A tube drawing mandrel construction comprising a mandrel shank, said shank having an enlarged skirt portion at one end. a stud positioned in said shank and extending outwardly of said skirt portion, a sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve being shorter than said stud, having a larger internal diameter than said stud and having a smaller external diameter than said skirt portion whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, and spring means carried on said stud for urging said mandrel or sleeve away from said shank, and said skirt portion being admeasured to overhang the rearward portion oi! said mandrel or sleeve when the latter is in its outermost position relative to said shank, whereby to pre-v vent tubing being drawn from working in behind said mandrel or sleeve.

5. A tube drawing mandrel construction comprising a mandrel shank, said shank having an enlarged skirt portion at one end, a stud positioned in said shank and extending outwardly of said skirt portion, a sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve being shorter than said stud, having a larger internal diameter than said stud and having a smaller external diameter than said skirt portion whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, and spring means carried on said stud for urging said mandrel or sleeve away from said shank, and said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in its outermost position relative to said shank, whereby to prevent tubing being drawn from working in behind said mandrel or sleeve, said shank and said stud being of tool steel and said mandrel or sleeve being of cemented tungsten carbide.

6. A tube drawing mandrel construction comprising a mandrel shank, said shank having an enlarged skirt portion at one end, a stud positioned in said shank and extending outwardly of said skirt portion, a sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve being shorter than said stud, having a larger internal diameter than said stud and having a smaller external diameter than said skirt portion whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, and spring means carried on said stud for urging said mandrel or sleeve away from said shank, said spring also serving as a shock absorber for said mandrel or sleeve when tubing being drawn leaves said sleeve, and said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in its outermost position relative to said shank, whereby to prevent tubing being drawn from working in behind said mandrel or sleeve.

7. A tube drawing mandrel construction comprising a mandrel shank, said shank having an enlarged skirt portion at one end, a stud positioned in said shank and having a uniformly diametered portion extending outwardly of said shank and of said skirt portion, a sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve being shorter than said stud, having a larger internal diameter than said stud and having a smaller external diameter than said skirt portion whereby said mandrel or sleeve may be displacedlongitudinally and laterally on said stud, and spring means carried on said stud for urging said mandrel or sleeve away from said shank, and said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in its outermost position relative to said shank, whereby to prevent tubing being drawn from working in behind said mandrel or sleeve.

8. A tube drawing mandrel construction comprising a mandrel shank, a stud positioned in said shank, said stud having portions of successively different diameters extending outwardly from said shank, said shank having an enlarged skirt portion and said stud extending outwardly of said skirt portion, a sizing mandrel or sleeve removably carried on the outermost of said portions of said stud, said mandrel or sleeve being shorter than said last-named portion of said stud and having a larger internal diameter than said last-named portion, and having a smaller external diameter than said skirt portion of said shank, whereby said mandrel or sleeve may be displaced both longitudinally and laterally on said stud, and spring means carried on said stud for urging said mandrel or sleeve away from said' shank and serving also as a shock absorber for said mandrel or sleeve, and said skirt portion of said shank being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in its outermost position relative to said shank whereby to prevent tubing being drawn from Working in behind said mandrel or sleeve.

9. A tube drawing mandrel construction comprising a mandrel shank having a threaded axially extending bore, a countersunk portion of different diameter adjacent the outer end of said threaded portion, and a second countersunk portion of still different diameter adjacent said first-named countersunk portion, said secondnamed countersunk portion defining a skirt portion for said shank, a stud threadedly engaging said threaded portion of said shank and extending outwardly of said skirt portion, a headed portion on said stud adjacent its outermost end, a sizing mandrel or sleeve carried on said stud, said mandrel or sleeve being shorter than said stud, having a larger internal diameter than said stud, and having a smaller external diameter than said skirt portion, whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, and spring means on said stud for urging said mandrel or sleeve towards said head and for'action as a shock absorber, and said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in abutment with said headwhereby to prevent tubing being drawn from working in behind said mandrel or sleeve.

10. A tube drawing mandrel construction comprising a mandrel shank, said shank having an enlarged skirt portion at one end, a stud positioned in said shank and extending outwardly of said skirt portion, a. tapered sizing mandrel or sleeve removably carried on Sfllld stud, said mandrel or sleeve being shorter than said stud,

having a larger internal diameter than said stud and having a smaller external diameter than said skirt portion whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, and spring means carried on sarld stud for urging said mandrel or sleeve away from said shank, and said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in its outermost position relative to said shank, whereby to prevent tubing being drawn from working in behind said mandrel or sleeve.

11. A tube drawing mandrel construction comprising a mandrel shank having a threaded axially extending bore, a countersunk portion of different diameter adjacent the outer end of said threaded portion, and a second countersunk portion of still different diameter adjacent said firstnamed countersunk portion, said second-named countersunk portion defining a skirt portion for said shank, a stud threadedly engaging said threaded portion of said shank and extending outwardly of said shirt portion, a headed portion on said stud adjacent its outermost end, a sizing mandrel or sleeve carried on said stud, said mandrel or sleeve being tapered and having a rounded or tapered peripheral rear edge and additionally tapered forward peripheral edge, and said mandrel or sleeve being shorter than said stud, having a larger internal diameter than said stud, and having a smaller external diameter than said skirt portion, whereby said mandrel or sleeve may be displaced longitudinally and laterally on Sfilld stud, and spring means on said stud for urging said mandrel or sleeve towards said head and for action as a. shock absorber, and said skirt portion being admeasured to overhang the rearward portion of said mandrel or sleeve when the latter is in abutment with said head whereby to prevent tubing being drawn from working in behind said mandrel or sleeve.

12. A tube drawing mandrel construction comprising a. mandrel shank, a retaining stud extending from an end of said shank, a. sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve having a larger internal diameter than the external diameter of said stud, and said mandrel or sleeve being shorter than said stud, whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, spring means carried on said stud serving as a shock absorber for said mandrel or sleeve, and a skirt portion extending from said shank and admeasured to overhang the rearward end of said mandrel or sleeve whereby to prevent tubing being drawn from working in behind said mandrel or sleeve.

13. A tube drawing mandrel construction comprising a mandrel shank, a retaining stud extendring from an end of said shank, a. sizing mandrel or sleeve removably carried on said stud, said mandrel or sleeve having a larger internal diameter than the external diameter 01' said stud, and said mandrel or sleeve being shorter than said stud, whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, spring means carried on said stud serving as a shock absorber for said mandrel or sleeve, and a skirt portion extending from said shrink and admeasured to overhang the rearward end of said mandrel or sleeve whereby to prevent tubing being drawn from working in behind said mandrel or sleeve, and means to attach said shank to a plug rod in tube drawing apparatus.

14. A tube drawing mandrel construction comprising a mandrel shank, a retaining stud extending from an end of said shank, a sizing mandrel or sleeve removably carried on said stud, salld mandrel or sleeve having a larger internal diameter than the external diameter of said stud, and said mandrel or sleeve being shorter than sa:ld stud, whereby said mandrel or sleeve may be displaced longitudinally and laterally on said stud, spring means carried on said stud serving as a shock absorber for said mandrel or sleeve, 10

and a skirt portion extending from said shank and admeasured to overhang the rearward end of said mandrelor sleeve whereby to prevent tubing being drawn from working in behind said mandrel or sleeve, and threaded means in conjunction with the other end of said shank for attachment of the latter to a restraining member or plug rod in tube drawing apparatus.

CARL H. WADELL. 

